Line protection MCCB — 125 A, 4-pole, TM210 release
The Siemens 3VA1112-4GD42-0AA0 is a SENTRON molded case circuit breaker (MCCB) configured for line protection, rated 125 A continuous at 40 °C with a 4-pole design and a TM210 thermal-magnetic overcurrent release. It carries a 121 kA interrupting capacity at 240 V, stepping down to 75.6 kA at 415 V and 52.5 kA at 440 V — numbers that govern its fault-clearing capability in low-voltage distribution panels. The TM210 release means the thermal element tracks overloads (typically 1.05–1.3× In) while the magnetic instantaneous pickup is fixed at 10× In — a standard curve for feeder and main breaker duty where coordination with downstream branch breakers is the priority. Rated insulation voltage (Ui) is 800 V, and the maximum DC operational voltage is 600 V, so this breaker can serve in mixed AC/DC panels as long as the DC interrupting ratings from the 3VA device manual are observed.
Thermal derating and panel integration
The 125 A rating holds flat from 40 °C through 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. In a sealed, uncooled enclosure at 55 °C ambient, expect to lose 3 A of headroom — plan the load accordingly. Dimensions are 130 mm height, 101.6 mm width, 70 mm depth — a 4-pole footprint that fits standard Siemens SENTRON mounting bases. Front IP40 protection means it is suitable for clean indoor panels; no washdown rating, so keep it out of wet zones. Maximum power loss is 28.1 W — a figure to include in the enclosure thermal budget, especially when multiple breakers are ganged in a row.
Lifecycle and sourcing posture
The N-conductor protection is designed at 100 % — full-rated neutral protection for 4-pole applications where the neutral carries the same current as the phases, typical in data-center or harmonic-rich loads.